00329nam a2200109Ia 4500008004100000040003800041100002300079245004400102250000800146260004800154300001700202211228s9999    xx            000 0 und d  cJayakar Knowledge Resource Centre  aFriedrichs, Kurt O 0aPeturbation of spectra in hilbert space  a1st  bAmerican mathematical societyaIslandc1965  axiii,178p p.